President Donald Trump is returning to Washington after his holiday break to face a hefty legislative to-do list, critical mid-term elections and perilous threats abroad.

Mr Trump is starting his second year in office after a lengthy sojourn at his private Palm Beach club in Florida capped by a New Year's Eve bash.

Before his departure, he fired angry tweets at Iran and Pakistan, criticising Islamabad for "lies & deceit" and saying the country had played US leaders for "fools", a reference to frustrations that Pakistan is not doing enough to control militants.

Pakistani foreign minister Khawaja Asif tweeted that his government was preparing a response that "will let the world know the truth".

North Korean leader Kim Jong Un said on Monday the US should be aware that his country's nuclear forces are now a reality, not a future threat. To that, Mr Trump only said: "We'll see."

The president is hoping for more legislative achievements after his pre-Christmas success on taxes.

He plans to host Senate majority leader Mitch McConnell of Kentucky and House Speaker Paul Ryan of Wisconsin at Camp David next weekend to map out the 2018 legislative agenda.

Republicans are eager to make progress before attention shifts to the mid-term elections.

The GOP wants to hold House and Senate majorities in 2018 but must contend with Mr Trump's historic unpopularity and some recent Democratic wins.

The president concluded 2017 with his first major legislative achievement - a law to cut taxes, beginning this year, for corporations and individuals at an estimated cost of 1.5 trillion dollars (£1.1 trillion) added to the national debt over 10 years.

The tax overhaul also will end the requirement, in 2019, that all Americans buy health insurance or pay a fine.

The White House has said Mr Trump will come forward with his long-awaited infrastructure plan in January.

Mr Trump has also said he wants to overhaul welfare and recently predicted Democrats and Republicans will "eventually come together" to develop a new healthcare plan.

Mr Ryan has talked about overhauling Medicaid and Medicare and other safety-net programmes, but Mr McConnell has signalled an unwillingness to go on that route unless there is Democratic support for any changes.

Republicans will have just a 51-49 Senate majority - well shy of the 60 votes needed to pass most bills - giving leverage to Democrats.

Congress also has to deal with a backlog from 2017. It must agree on a spending bill by January 19 to avert a partial government shutdown.

He spent his last day in Florida as he spent most other days - visiting his golf course and tweeting.

On Pakistan, he said: "The United States has foolishly given Pakistan more than 33 billion dollars in aid over the last 15 years, and they have given us nothing but lies & deceit, thinking of our leaders as fools. They give safe haven to the terrorists we hunt in Afghanistan, with little help. No more!"

The US has long accused Islamabad of allowing militants to operate relatively freely in Pakistan's border regions to carry out operations in neighbouring Afghanistan.

In August, the US said it would hold up 255 million dollars (£188 million) in military assistance for Pakistan until it cracks down on extremists threatening Afghanistan.

On Iran, Trump kept up his drumbeat in support of widespread anti-government protests. He tweeted Monday that Iran is "failing at every level" and it is "TIME FOR CHANGE."